Definition of nightdress in English:

noun

Entire families known to me previously only fully dressed in daytime clothing were wearing pajamas and nightdresses under their bathrobes and milling around in their slippers at dawn as if driven from their homes by an earthquake.

Women in nightdresses and nightgowns and men in trousers and shorts exited their homes in the utmost haste, murmuring amongst themselves.

While the guards still wore their uniform, the nobles were in their nightdresses and dressing gowns.